<?php
$xml_header = "<?xml version='1.0' encoding='utf-8'?><xml/>";
$xml = new SimpleXMLElement($xml_header);
$xml->addChild("first_string","this is <mystring> € Euro &; puntk &groetjesaanjemoeder; groetjes & en ");
$xml->addChild("second_string","this is <mystring>");
echo $xml->first_string . $xml->second_string;